I use geeqie on linux as a digital contact sheet. Images I’m interested in get sent to Darktable, where I do the bulk of the work. I finish with darktable by saving a tif, and then spawn Gimp (from the geeqie file browser) for final touch up. And then save a final jpeg or png.
I do a lot of bird photography. I like to use Gimp threshold masking as a close to final step in order to isolate the whites of bird’s eyes. And then lighten the eye a bit. A parametric mask combined with drawn mask in in darktable can often do that too, but never as accurately as Gimp threshold masking. That’s one motivation for using Gimp at all. That scenario does raise a few questions.
One question involves levels. If I have a relatively monochrome or flat lighted subject I might use levels in darktable, thereby stretching the histogram so the darkest values become black or near black and the lightest values become white or near white.
But when I get to Gimp its “levels” histogram nearly always looks (in Gimp) as if it had not already been stretched out in darktable. This doesn’t make sense to me.
Another problem with that scenario is that Gimp’s noise reduction and sharpening don’t seem to be as good as Darktable’s. But now it’s too late to go back.